Duplex circuit.



' L. ESPENSCHIED.

. DUPLEX CIRCUIT.

APPLICATION men on. 13. 1915.

l,%3,%? Patented July 17, 1917.

I If i uuirnn --i;nnn 'rriia ff t orn nsrnn'eonrnio, or mountain, new"some assicnon T AMnnIcAn rnnnrnonn lowedhy the flux clue tothe sidecircuit and i i integral.

AND TELEGRAPH C'DMPANY, A CORPORATION 03? NEW YORK.

JDTJ'TBLEX CIRCUIT.

Specification of Letters Patent.

Patented can it, an.

Application filed (ictoher 13, 1915. Serial No. 55,715.

To all whom iz -may concern:

Be it known that l. LLOYD Esrnusonrnn i l 9 residing at Brooklyn, in thecounty of as those employed in telephony and compris lug physlcal andphantom circuits, and espe- ,clally such. inductance devices as loadingcoils adapted ior use therein. its purpose isQto' provide a device ofthis character, which, independently of the other inductance devices ofthe duplex circuit; shall produne its effect in a plurality of componentcircuits. The invention further has for its object the furnishing ofmeans for controlling the ratio of the plural inductance citiects.

Figures 1, 4 and 5 oithe accompanying drawing show the inventiondiagrammatically in its application to the loading of a duplex telephonecircuit; and Figs. :2 and 3 illustrate, respectively, the pathsfolphantom circuit currents in the core of the device shown in Fig. 1.

, Thecharacters A, B and C, D deslgna-te the hue conductors of twophysical telephone circuits 111 whlch talking current flows in serlesthrough both pairs oi eon- .ductors, as indicated by" the full. anddashed arrows, respectively. By any suitable 'ineans these physicalcircuits are made to serve also as a phantom circuit through whichtalking current passes in series through the pairs of conductors eachjoined inparallel, as the dotted arrows indicate. At proper intervals inthese physical or e circuits A, B and C, D, loading coils "and F arerespectively connected, these b 'iing related as is customary in loadingcoil practice he that they have no mutual. inductive action. As thesecoils are identian. but one will be referred to in detail.

ll. core G of magnetic material is formed in s half portions 10 and 11,preferably These, portions, as illustrated, form" a toroid. thoughanyother closed figlar in cross-section.

ure, preferably symmetrical, as a rectangle, may be employed, and eventhe toroid is not to he understood as necessarily circu Confined to eachhalf portion of the core is a line winding included in the conductor ofa side circuit, the

Winding L, for example, being united with v the, conductor A and theWinding L with the conductor B. These windings may be so arranged thattheir chief effect is upon;

the side circuit in which the coil is located or upon the phantomcircuit, by respectively connecting L and L with their inductancesmutually aiding for side circuit current and mutually opposing t'orphantom cire cuit current, as exemplified in Fig.1,- or mutuallyopposing for side, circuit current and mutually aiding for phantomcircuit current, as in at. Only the former, as illustrated in Fig. 1 ofthe drawing will be particularly considered. Between windings L and Lthe junctions of the'halves of the toroid or primary core portion arejoined by a preferably integral magnetic inner secondary portion in theform of a die-metric yoke I Upon the windings between traversedby sidecircuit current, magnetic flux is generated in the core, which is asappears in Fig. 2, and under such conditions the mu tual incluctances ofthe two windings are added to their self inductanccs toloadlt he sidecircuit A, B. When, however, phan' tom current flows through thewindings, consequent poles are produced at the junctions of the halfportions 10 and 11, the polarity of which at any instant may beindicated by the signs and Figs. and 3. Connecting these consequentpoles the yoke or hranchcore 12 serves as a return'path of lowreluctance for the phantom flux, as illustrated in Fig. 3. Because ofthe loose inductive coupling caused by separating the line windings upondili'crent portions ofv the core and giving apath of low reluctance todivert the flux generated by each inding from its companion, theinductancesfor phantom current do not neutralize as they do in theclosely coupled standard loading unbalance between. circuits.

the, symmetrical design, the coil units are about practically the entirecircumference mutual inductances are zero and therefore there is nopossibility of a mutual inductance By virtue of balanced with respect toresistance, inductance and admittance. Therefore, there will betheoretically no crosstalk between the cir-' cuits. Such an arrangementas has just been described gives a relatively low ratio, about 0.2,between the phantom circuit and side' circuit inductances,while a muchhigher ratio than this is usually desired. To enablethis ratio to becontrolled so that, the proper relation may be established, auxiliarymeans are provided for varying either the side circuit or phantomcircuit inductances. As illustrated in Fig. 1 this means takes the formof windings 1 and 1", belonging respectively to the primary inductancewindings L andL In the present instance it is'assumed that the ratioof'the phantom to the sidecircuit inductance is to be increased.

In such case, though the auxiliary windings may be upon the outer coreportlons, as in--- dicated in Fig. 5, they are preferably placed,

as shown in Fig. 1, upon the yoke'12 which 4 is traversed by all thefiux due to the phantdmnircuit. This requires but half as many turns ofauxiliazy winding as would be necessary were they upon the portions 10and 11 in which the phantom flux is div1ded (see Fig. 3.). The auxiliarywindings l and 1 v are so connected as to be mutually opposing for sidecircuit current and hence, mutually aiding for phantom circuit current,while together they aid the primary windings for phantom current. Theratio sought may be obtained by altering the number of their turns.

In addition to the function of the auxiliary windings of controlling theratio of phantom to side circuit inductances, their effect should benoted in decreasing the magnetic leakage produced by the phantomcurrentfrom the consequent poles between the core portions 10 a-nd;11.At thispoints flux, 1n addition to traversing the yoke 12 leaves andenters the core in proportion to the magnetic reluctance of the yoke.This leakage flux passing through surrounding tance of the phantom,create poles at the points indicated opposite in sign to those theinvention claimed in my copending application Serial No. 55,.'Z14,afi1edOctober 13,

I claim:

1. The combination with two physical circuits consisting of lineconductors together furnishing a phantom circuit, of deviceshavingwindings included in the conductors of said hysical circuits toproduce inductance e ects therein, said devices being inductivelyindependent, and the windings of each device being loosely coupledinductively whereby they produce inductance effects in the phantomcircuit.

, 2. The combination with two physical circuits consisting of lineconductors together furnishing a' phantom circuit, of devices havingwindings included in the conductors of said hysical circuits to produceinductance e ects therein, said devices being inductively independent,and the self inductances of the windings being eflective in the phantomcircuit.

3. The combination with two physical circuits consisting of" lineconductors together furnishing aphantom circuit, of an induchaving anouter portion forming a closed figwe and a portion connecting the sidesthereof, primary magnetizing windings upon the outer portion of thecore, and auxiliary windings for the magnetizing windings upon theconnecting portion.

6. A loading coil comprising a toroidal core having a diametric yoke,inductance windings upon the toroid, and an inductance controllingwinding upon the yoke.

7. The combination with physical circuits consisting of line conductorstogether furnishing a phantom circuit, of a loading coil comprising atoroidal core having a diametric yoke, primary inductance windings uponthe toroid included in the conductors, and an inductance controllingwindin for each primary winding, said contro ling windings beingsituated upon the yoke.

8. Aniniuotenoe device comprising a name to this specification, in theresenoe of magnetic core having winding po 'tions end two subscribingwitnesses, this 2 th day of a; portion connecting the junctions of theSeptember, 1915. Winding portions, a magnetizing Windin LLQYDESPENSCHIED. 5 upon each of the firshnemed portions, ang Witnesses:auxiliary windings associated with the core. CHAS. G. Hnmnn, Jr",

In testimony whereof, I have signed my A; O. FANoA.

